USING SEMANTIC AUTHORING FOR BLISSYMBOLS COMUNICATION BOARDS

1. USING SEMANTIC AUTHORING FOR BLISSYMBOLS COMUNICATION BOARDS USING SEMANTIC AUTHORING FOR BLISSYMBOLS COMUNICATION BOARDS Yael Netzer and Michael Elhadad Dep. of Computer Science, Ben Gurion University, Beer Sheva, Israel {yaeln, elhadad}@cs.bgu.ac.il BLISSYMBOLS Abstract Natural language generation (NLG) refers to the process of producing text in a spoken language, starting from an internal knowledge representation structure. Augmentative and Alternative Communication (AAC) deals with the development of devices and tools to enable basic conversation for language-impaired people. We present an applied prototype of an AAC-NLG system generating written output in English and Hebrew from a sequence of Bliss symbols. The system does not “translate” the symbols sequence, but instead, it dynamically changes the communication board as the choice of symbols proceeds according to the syntactic and semantic content of selected symbols, generating utterances in natural language through a process of semantic authoring. Blissymbolics (bliss in short) is a graphic meaning-referenced language, created by Charles Bliss to be used as a written universal language. It was first published in 1949 and elaborated later in 1965 in his book Semantography [Bliss, 1965]. Bliss, a survivor of the Holocaust, was infuenced by the Chinese orthography system and his life experience, and wished to establish an understandable written language that could be used by people of different nations and languages {as he believed that language misunderstanding is a main cause of wars in the world. In 1971, the bliss symbol system was first used for communication with severely language-impaired children. Augmentative and Alternative Communication (AAC) • Augmentative and alternative communication (AAC) is concerned with studying methods of communication that can be added to natural communication (speech and writing), especially when an individual lacks some of the skills to achieve it. • AAC devices are characterized by three aspects [Hill and Romich, 2002]: • 1. Selection method • 2. Input language • 3. Output medium • In a computerized system [McCoy and Hershberger, 1999], a processing method aspect is added to this list. This method refers to the process which creates the output once symbols are inserted. Generating Messages via Translation Previous works dealing with translating telegraphic text, such as (Grishman and Sterling, 1989), (Lee et al., 1997) requires to identify dependency relations among the tokens of the telegraphic input. Rich lexical knowledge is needed to identify possible dependencies in a given utterance, i.e., to find the predicate and to apply constraints, such as selectional restrictions to recognize its arguments. Similar methods were used for AAC applications, COMPANSION (McCoy, 1997) for example – where the telegraphic text is expanded to full sentences, using a word order parser, and a semantic parser to build the case frame structure of the verb in the utterance, filling the slots with the rest of the content words given. The system uses the semantic representation to re-generate fluent text, relying on lexical resources and NLG techniques. Symbol types of Blissymbols Ontology fragments of concepts and relations Indicators modify the lexical category of the symbol • Generating Messages via Semantic Authoring • Semantic parsing is avoided by constructing a semantic structure explicitly while the user inputs the sequence incrementally. It combines three aspects into an integrated approach for the design of an AAC system: • Semantic authoring drives a natural language realization system and provides rich semantic input. • A display is updated on the fly as the authoring system requires the user to select options. • Ready-made inputs, corresponding to predefined pragmatic contexts are made available to the user as semantic templates. Each time a symbol is chosen, the system converts the current expression to a conceptual graph (CG), maps the CG to a FUF Functional Description (FD), which serves as input to the lexical chooser; lexical choice and syntactic realization are performed, and feedback is provided in English or Hebrew. If the chosen symbols so far were I and to play, the conceptual graph built is: [Play]-(Actor1)->[Person:{I}] Modifiiers in Blissymbols Generation Process (lexical choice and syntactic realization) This CG is transformed into an FD of the appropriate form and is unified with the lexical chooser, using the information on the verb play as embedded in the concept representation: <description descriptionNumber="0.2" primary="Intransitive" secondary="+ with-NP" xtag="0.2"/> The intransitive structure is chosen since there is only one participant given, and the resulting string generated is I play. However, once Pablo was chosen as the second actor relation and the CG is complete: [Play]- (Actor1)->[Person:{I}] (Actor2)->[Person:Pablo] The system consults the lexical chooser again and unifies the given input with the verb's possible syntactic structures following its alternation, in this case: Alternation alternation-of-verb-play-simple_reci_intrans: [struct with-np] [structsubj-and-np-v] This syntactic alternation indicates that the clause: I play with Pablo can be generated. Alternatively, following the possible choice of the alternation which is available for the verb play with its current sense, the structure (STRUCT SUBJ-AND-NP-V) can be chosen as well, with the final output Pablo and I play. In the GUI of the system, a button can switch the generation of the clause from one argument structure to the next, according to the alternations supported by the verb. Next, the system offers the opportunity to add sentence modifiers such as time and location and other possible circumstances. Various realizations of the verb ‘to be’ in Blissymbols Selected References Ofer Biller, Michael Elhadad, and Yael Netzer. 2005. Interactive authoring of logical forms for multilingual generation. In Proceedings of the 10th workshop of ENLG, Aberdeen, Scotland. Charles K. Bliss. 1965. Semantography (Blissymbolics). Semantography Press, Sidney. D. Jeffery Higginbotham. 1995. Use of nondisabled subjects in AAC research: Confessions of a research infidel. AAC Augmentative and Alternative Communication, 11, March.AAC Research forum. Kathleen F. McCoy and Dave Hershberger. 1999. The role of evaluation in bringing NLP to AAC: A case to consider. In Filip T. Loncke, John Clibbens, Helen H. Arvidson, and Lyle L. Lloyd, editors, AAC: New Directions in Research and Practice, pages 105–122. Whurr Publishers, London. Kathleen F. McCoy. 1997. Simple NLP techiques for expanding telegraphic sentences. In Proceedings of workshop on NLP for Communication Aids, Madrid, July. ACL/EACL. Pascal Vaillant. 1997. A semantic-based communication system for dysphasic subjects. In Proc. of the 6th conference on AI in Medicine Europe (AIME’97), Grenoble, France, March. The lexicon can be used either as a stand-alone lexicon for reference or as part of an application. The design of the lexicon takes advantage of the unique properties of the language. Technically, only a set of atomic shapes is physically drawn while combined symbols are generated automatically, following the symbol's entry in a database that was constructed from the Hebrew and English Bliss Dictionaries. The lexicon was implemented in a way that allows searches through either textual (a word), or semantic components (e.g., "all symbols that contain a wheel"), or by forms (e.g., "all symbols that contain a circle").